It is known that clubfoot is one of the most common serious congenital deformities of the musculoskeletal system in newborns, with a frequency of 1 to 6 in 1000 in the Caucasian population. The foot has a typical appearance of pointing downwards and twisted inwards. Since the condition starts in the first trimester of pregnancy, the deformity is quite established at birth, and is often very rigid. There are three main types of defect: Equinovarus, Calcaneus valgus, and Metatarsus varus or adductus. Equinovarus is the most severe type of the defect, wherein the foot is twisted inward and downward so that the patient cannot place the insole flat on the ground and must walk on the ball, the side, or even the top of the foot. Calcaneus valgus is the moderately severe form of the defects, wherein the foot is angled upward and outward so that the patient has to walk on the heel or the inner side of the foot. Metatarsus varus or adductus is the mildest form of the defect, does not involve the ankle, but only the bones and connective tissues of the foot, causing the front part to turn inward.
The cause of the deformity is unknown. Irrespective of its causes, during development, the posterior and medial tendons and ligaments (in the back and inside) of the foot fail to keep pace with the development of the rest of the foot. As a result, these tendons and ligaments tether the posterior and medial parts of the foot down, causing the foot to point downwards and twist inwards. The bones of the feet, therefore, are held in an abnormal position. Over time, if uncorrected, the bones will become misshapen.
Clubfoot does not cause pain in the infant. Because it is so obvious, it is usually discovered at birth. If left untreated, the deformity persists. It worsens over time, with secondary bony changes developing over years. An uncorrected clubfoot in the older patient or adult is unsightly, and crippling. The patient walks on the outside of the foot, which is not meant for weight-bearing.
There are different treatment options for clubfoot, including serial casting, splints, the Ponsetti Method, and surgery. The Ponsetti Method includes casting, cutting of the Achilles tendon, and subsequently wearing corrective foot orthosis. Typically, the treatment involves weekly stretching of the foot deformity, followed by the application of long plaster leg casts. Before the application of the final leg cast, the physician usually performs a tenotomy, a percutaneous heel cord lengthening to correct the hindfoot deformity. The patient wears the final cast for three weeks to allow the tendon to heal. The patient then wears a corrective foot orthosis full time for three months, followed by night and naptime wear for up to four years to prevent the deformity from recurring.
Compliance with corrective foot orthosis is essential to prevent relapse of the clubfoot deformity. If the corrective foot orthosis is not worn, reocurrence generally is inevitable and the patient is faced with major reconstructive foot surgery to correct the clubfoot. Children that have the major surgery often suffer stiffness, pain, and arthritis in early adulthood.
The main reasons for noncompliance with corrective foot orthosis is that they limit the mobility of the patient, are uncomfortable, and/or form blisters on the back of the patient's heels. For example, one corrective foot orthosis includes a pair of shoes mounted on a flat bar. This corrective device is extremely uncomfortable because it maintains the feet in almost rigid positions. Another corrective foot orthosis includes a parallelogram link as a cross bar between the patient's feet. This corrective device, while allowing movement of each foot forwards and backwards, restricts freedom of movement of either foot up and down. Upward and downward movement is restricted with this type of device because articulation occurs in the middle of the cross brace rather than by the shoe or foot orthosis. In addition it does not address the blisters and friction created by the shoe on the patient.
It is thus desired to have a corrective foot orthosis device wherein a patient's feet are maintained at a desired angle while allowing the patient's feet to have vertical mobility and preventing blister formation.